I had previously setup gphotoshow as my login screensaver when I had version 4 (by copying the registry keys), but after upgrading to version 6, I got an error message (only on the login screen) stating that I had not yet set a folder for picture files. So after some research I discovered that I also had to copy the registry key from Current User to S-1-5-19. Now the pictures show up at the login screen, but the only problem is that it says it's an unregistered version and I only have a 30 trial period. Is there any way to fix this?

gPhotoShow Pro has a function to set it as logon screen saver without manually editing the registry. Go to the "System Settings" page in the gPhotoShow Pro configuration window, click on "Set gPhotoShow & Save" it will take care of saving the current settings to correct registry location and set everything is needed to avoid that issue.